package startrpc

import (
	"context"
	"fmt"
	"github.com/liserc/opensocket-server/pkg/config"
	"github.com/liserc/opensocket-server/pkg/prommetrics"
	discovery2 "github.com/liserc/opensocket-server/tool/discovery"
	"github.com/liserc/opensocket-server/tool/errs"
	"github.com/liserc/opensocket-server/tool/log"
	mw2 "github.com/liserc/opensocket-server/tool/mw"
	"github.com/liserc/opensocket-server/tool/network"
	"google.golang.org/grpc/status"
	"net"
	"net/http"
	"os"
	"os/signal"
	"strconv"
	"syscall"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
)

// Start rpc server.
func Start[T any](ctx context.Context, discoveryConfig *config.Discovery, prometheusConfig *config.Prometheus, listenIP,
	registerIP string, rpcPort int, rpcRegisterName string, share *config.Share, config T, rpcFn func(ctx context.Context,
	config T, client discovery2.SvcDiscoveryRegistry, server *grpc.Server) error, options ...grpc.ServerOption) error {
	// RPC initializing
	log.CInfo(ctx, "RPC server is initializing", "rpcRegisterName", rpcRegisterName, "rpcPort", rpcPort,
		"prometheusPort", prometheusConfig.Port)

	rpcTcpAddr := net.JoinHostPort(network.GetListenIP(listenIP), strconv.Itoa(rpcPort))
	listener, err := net.Listen(
		"tcp",
		rpcTcpAddr,
	)
	if err != nil {
		return errs.WrapMsg(err, "listen err", "rpcTcpAddr", rpcTcpAddr)
	}
	defer listener.Close()
	client, err := discovery2.NewDiscoveryRegister(discoveryConfig)
	if err != nil {
		return err
	}

	defer client.Close()
	client.AddOption(mw2.GrpcClient(), grpc.WithTransportCredentials(insecure.NewCredentials()), grpc.WithDefaultServiceConfig(fmt.Sprintf(`{"LoadBalancingPolicy": "%s"}`, "round_robin")))
	registerIP, err = network.GetRpcRegisterIP(registerIP)
	if err != nil {
		return err
	}

	if prometheusConfig.Enable {
		options = append(
			options, mw2.GrpcServer(),
			prommetricsUnaryInterceptor(rpcRegisterName),
			prommetricsStreamInterceptor(rpcRegisterName),
		)
	} else {
		options = append(options, mw2.GrpcServer())
	}

	srv := grpc.NewServer(options...)

	err = rpcFn(ctx, config, client, srv)
	if err != nil {
		return err
	}

	err = client.Register(
		rpcRegisterName,
		registerIP,
		rpcPort,
		grpc.WithTransportCredentials(insecure.NewCredentials()),
	)
	if err != nil {
		return err
	}

	var (
		netDone = make(chan struct{}, 2)
		netErr  error
	)
	if prometheusConfig.Enable {
		go func() {
			prometheusPort := prometheusConfig.Port
			cs := prommetrics.GetGrpcCusMetrics(rpcRegisterName, share)
			if err := prommetrics.RpcInit(cs, prometheusPort); err != nil && err != http.ErrServerClosed {
				netErr = errs.WrapMsg(err, fmt.Sprintf("rpc %s prometheus start err: %d", rpcRegisterName, prometheusPort))
				netDone <- struct{}{}
			}
		}()
	}

	go func() {
		err := srv.Serve(listener)
		if err != nil {
			netErr = errs.WrapMsg(err, "rpc start err: ", rpcTcpAddr)
			netDone <- struct{}{}
		}
	}()

	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, syscall.SIGTERM)
	select {
	case <-sigs:
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()
		if err := gracefulStopWithCtx(ctx, srv.GracefulStop); err != nil {
			return err
		}
		return nil
	case <-netDone:
		return netErr
	}
}

func gracefulStopWithCtx(ctx context.Context, f func()) error {
	done := make(chan struct{}, 1)
	go func() {
		f()
		close(done)
	}()
	select {
	case <-ctx.Done():
		return errs.New("timeout ctx graceful stop")
	case <-done:
		return nil
	}
}

func prommetricsUnaryInterceptor(rpcRegisterName string) grpc.ServerOption {
	getCode := func(err error) int {
		if err == nil {
			return 0
		}
		rpcErr, ok := err.(interface{ GRPCStatus() *status.Status })
		if !ok {
			return -1
		}
		return int(rpcErr.GRPCStatus().Code())
	}
	return grpc.ChainUnaryInterceptor(func(ctx context.Context, req any, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (any, error) {
		resp, err := handler(ctx, req)
		prommetrics.RPCCall(rpcRegisterName, info.FullMethod, getCode(err))
		return resp, err
	})
}

func prommetricsStreamInterceptor(rpcRegisterName string) grpc.ServerOption {
	return grpc.ChainStreamInterceptor()
}
